1. Field of the Invention
This invention is believed to be found in the apparatus pertaining to the forming of air-cushioning material. The apparatus for forming air-cushioning dunnage is well known, but the forming roll providing a simple and positive control of the surface temperature of the roll is unique.
2. Description of the Prior Art
Air-cushioning material is well known as packing dunnage both for its low cost and light weight and also for its convenience and strength. This dunnage product utilizes flexible plastic sheet material and in the present invention the forming roll and its construction are directed to and toward producing thermoplastic films in strip or roll form. The roller of this invention receives a plastic sheet which is heated to bring a surface to a temperature in the proximity of fusion, welding or melting. This heated sheet is brought to this roller where it is shaped by cavities provided in an embossing pattern. Vacuum is used to form this sheet. Another sheet or strip of film is heated to a fusion or welding temperature and then laminated to the thermoformed sheet of film. This roller is uniquely constructed so that the temperatures of the film surfaces at the weld which are produced in conjunction with this roller are sufficient for the weld to be achieved, and are of course equalized when fusion or welding is achieved.
There are many patents in the air cell cushioning dunnage field, such as, for instance, Australian Pat. No. 160,551, published Oct 29, 1953, and U.S. Pat. Nos. 3,018,015; 3,142,599; 3,231,454; 3,285,793; 3,349,990; 3,577,305; 3,389,534; 3,523,055; 3,575,781; 3,616,155; 3,785,899; 3,817,803; 3,837,990; 3,837,991; 3,868,056; 4,076,872; and 4,096,306. In addition, U.S. Pat. Nos. 3,416,984 and 3,392,081 show basic construction methods, and U.S. Pat. Nos. 4,415,398 and 4,427,474 show plural sheets and/or drum apparatus. The prior art does not show or suggest the construction of the roller of this invention which provides a rugged and foolproof temperature control of the surface of the roller. This construction of the roller lends itself to the minimum of attention and maintenance.